Mr. Hill is operating a digital camera. His friend David Hughes is manipulating a model on a metal table. The model is a three-pound fetal pig.

"Awesome," Mr. Hill said.

Mr. Hughes and Mr. Hill, both 37, spent a week dissecting the fetal pig in a makeshift lab attached to Mr. Hill's garage near Tampa, taking thousands of photos.

They then turned those images into a computer program that permits users -- mostly high school students -- to simulate the fetal pig dissection. Point-and-click versions of scalpels, scissors and even saws allow students to find, remove and examine organs without ever smelling formaldehyde. Hundreds of schools, which are already using software as an alternative to animal dissection will receive the fetal pig module later this month. Other companies including Biolab, Digital Frog and DryLab also offer dissection software.

Nearly a dozen states have laws or regulations requiring public schools to offer students such an option. Animal protection groups have lobbied against dissection and many students have decided that dissecting real animals is not for them.

Mr. Hill said that he and Mr. Hughes, whose six-year-old company is called Froguts, are "on the fence" about whether students should be required to dissect. "We're providing a tool for people to use if they want it," he said.

In 1999, Mr. Hill's stepdaughter, Erin, who was then 11, dissected a frog in school. "About a week later, when I asked her questions, she had a hard time describing the organs in detail," said Mr. Hill, then a high school science teacher. That got him thinking about how he might simulate the dissection experience, in a format that allows users to repeat procedures and then review what they have done -- and, he said, "without wasting another batch of frogs."

The men are going for verisimilitude. When they decide to use a tiny rotary saw to remove the top portion of the pig's skull, they add a similar saw -- in icon form -- to the tool kit in their program.

"If there was a USB device that would let us simulate the smell," Mr. Hughes joked, "we'd use it."

The company sends to subscribing schools compact discs with virtual dissections of six organisms. The fetal pig will be the company's first mammal, and the two men are excited about it. They spent a day examining the animal's exterior, then skinning it.

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"We want to do a neat job," Mr. Hughes said. Along the way, they "sexed" the pig, looking for a scrotum or genital papillae -- and making notes so that students could repeat the procedure.

Of course, each organism is unique, Mr. Hughes said. One of the things students get out of actual dissections, he said, is the realization that the pig in front of them is different from any other pig. "Theirs will never look exactly like the one in the textbook."

That is lost with virtual dissection.

But for students who will not dissect, they say, there is more to gain than to lose from a computer simulation. "Teachers say, 'We've been looking for a way out of dissection, and you've given it to us,"' Mr. Hughes said.

The Froguts founders met at Gibbs High School in St. Petersburg in the 1980's. They stayed friends when Mr. Hughes left for Seattle, where he became the director of Web development for Searchopolis, a portal geared to children. "He was pulling in six figures," said Mr. Hill, who had stayed in Florida to teach. "It didn't look like working together was in the cards."

But the dot-com bust left Mr. Hughes looking for another outlet for his interests in computers and biology. (When he is not working for Froguts, he is the infrastructure and software architect for the University of Washington School of Nursing.)

Mr. Hill began developing dissection software in 1999, and in the spring of 2001 offered a frog dissection program on the Internet, free of charge. After a number of search engines directed users to the site, "our Internet service provider couldn't handle all the traffic," said Mr. Hughes, who joined the company at the end of 2001.

Mr. Hughes said that schools pay about $300 a year for a license to use all of the Froguts software for a year. There have also been many sales to parents who teach their children at home, he said. (The cost is $75 via www.froguts.com.)